Effect of chemical enhancers on percutaneous absorption of daphnetin in isopropyl myristate vehicle across rat skin in vitro

The percutaneous absorption properties of daphnetin with chemical penetration enhancers were investigated to explore the feasibility of daphnetin as a candidate for transdermal delivery to treat arthritis. Permeation experiments were carried out in vitro using 2-chamber diffusion cells in isopropyl myristate (IPM) vehicle using rat abdominal skin as a barrier. Various enhancers were employed, including O-acylmenthol derivatives synthesized in the laboratory and many conventional enhancers. Among the O-acylmenthol derivatives, 2-isopropyl-5-methylcyclohexyl 2-hydroxypanoate (M-LA) demonstrated a significant enhancing effect on daphnetin permeation. The highest degree of enhancement was obtained when NMP combined with Span 80 and the cumulative transport was 667.29 μg/cm² over 8 h. The solubility parameters, vehicle/stratum corneum partition, and diffusion coefficients were calculated to clarify the enhancing mechanism of classic enhancers on daphnetin. In conclusion, these findings allow a rational approach for designing an effective daphnetin transdermal delivery system.     

Enhancement of nortriptyline penetration through human epidermis: influence of chemical enhancers and iontophoresis

Different known percutaneous chemical enhancers and iontophoresis have been tested in-vitro to study their ability to increase transdermal absorption of nortriptyline hydrochloride (20 mg mL(-1)). The chemicals 1-dodecanol, Span 20, Azone, (R)-(+)-limonene or isopropyl myristate were used as an overnight pretreatment at 5% (w/w) in ethanol. Furthermore, isopropyl myristate (20%, w/w) and propylene glycol (15%, w/w) were tested in the same vehicle. Iontophoresis was applied directly to the nortriptyline hydrochloride donor solution for three different concentrations (20, 2 and 0.5 mgmL(-1)). The chemical enhancers slightly increased the nortriptyline transdermal flux but iontophoresis was more efficient. In this case, nortriptyline transdermal flux was concentration dependent, having a higher flux when the concentration was lowered. Therefore, iontophoresis was the most suitable technique to increase transdermal absorption of nortriptyline and it could be an alternative method to provide therapeutic concentrations of this drug in smoking cessation treatment.     

Effects of penetration enhancers on in vitro permeability of meloxicam gels

Meloxicam (MLX) was formulated as a 0.3% hydroxypropylcellulose (Klucel) gel. The effect of four different combinations of co-solvents (ethanol, glycol-PEG-400, propylene glycol, and water) on MLX permeability was determined in vitro throughout isopropyl myristate (IPM)-saturated cellulose membranes. The gel consisting of 2.5% Klucel, propylene glycol, ethanol, and water (1:1:1) showed superior permeability properties and it was selected as the base-gel to investigate the effect of three levels of the penetration enhancers: dimethylsulfoxide (1, 5, and 10% DMSO), tween20 (1, 2, and 5% TW20), oleic acid (0.4, 1, and 5% OA), and menthol (1, 2.5, and 5% MT). In vitro permeability was determined throughout IPM-saturated cellulose membranes and human cadaver skin. DMSO and TW20 did not improve permeability of MLX compared to the control gel at any of the levels tested. Menthol produced a statistically significant (P<0.001), dose proportional increase in MLX flux with a peak at 5% (2.43+/-0.47 microg/cm2/h). Conversely, addition of OA peaked at 1% but decreased at the higher level (5%). There was no significant difference between the MLX amount recovered in stratum corneum and dermis across the different formulations tested. These findings show that the 0.3% MLX gel formulation containing 5% menthol can possibly deliver therapeutically relevant doses of MLX.     

In vitro evaluation of nimodipine permeation through human epidermis using response surface methodology

An optimization technique (response surface method) was used in order to investigate the effect of the combination of two enhancers, namely caprylic acid and cineol on nimodipine's permeation through human cadaver epidermis. Using this quadratic model it was found that at 24 h the increase of the permeation of nimodipine it was mainly due to the effect of caprylic acid. On the contrary, it was shown that at 48 and 72 h the combination of the two enhancers contributed to the increase of the permeation. The greater Q(gel)/Q(control) values, at all time intervals (24, 48 and 72 h), were obtained when the concentration of cineol and caprylic acid range from 3.0 to 5.0% (v/v) and 8.0 to 9.5% (v/v), respectively.     

不同透皮吸收促进剂对左旋肉碱透皮特性的影响

目的:选择适宜的透皮吸收促进剂增加左旋肉碱的透皮百分率。方法:使用改良Franz体外释药装置,用RP-HPLC法检测接收液中左旋肉碱的浓度,计算药物的透皮累积释放量,采用滞留时间法求算经皮渗透相关系数,考察不同用量的丙二醇、尿素、氮酮对左旋肉碱的促透作用。结果:左旋肉碱的溶液在体外透皮释放试验中有透皮吸收。不同种类及不同用量的吸收促进剂对左旋肉碱的促透作用不同,且随着透皮时间的延长,促透量显著增加。3种透皮吸收促进剂中尿素和丙二醇的促透作用较好,氮酮的促透作用稍差。结论:透皮吸收促进剂能够增加左旋肉碱的透皮百分率,其中2.5%的丙二醇促透作用最强。     

渗透促进剂对葛根素角膜透过性的影响

目的研究葛根素(puerarin)的角膜透过性,为其处方设计提供理论基础。方法采用体外扩散实验以林格溶液为扩散介质考察在多种渗透促进剂条件下PUE的离体兔眼角膜透过性。结果10 g.L-1吐温80和5 g.L-1乙二胺四乙酸二钠(EDTA)分别使PUE的表观渗透系数增加到1.69和2.10倍,与对照组呈现显著性差异(P<0.01),而20 g.L-1羟丙基-β-环糊精(HP-β-CD)与1 g.L-1月桂氮卓酮(azone)未能显著增大PUE的表观渗透系数(P>0.05);5 g.L-1乙二胺四乙酸二钠(EDTA-2Na),10 g.L-1吐温80能显著缩短PUE透过角膜的滞后时间(P<0.01);而20 g.L-1羟丙基-β-环糊精(HP-β-CD)与1 g.L-1月桂氮卓酮(azone)未能显著缩短PUE的滞后时间(P>0.05);所有渗透促进剂对眼组织均没有显著刺激性。结论5 g.L-1的EDTA-2Na能够显著增加PUE的表观渗透系数并能显著缩短其角膜透过时间,且对角膜无明显刺激性。     

Effects of penetration enhancers on Shuangwu traumatic formula: In vitro percutaneous absorption and in vivo pharmacodynamic evaluation of an herb medicine

The purposes of this study were to improve the transdermal permeation of the Shangwu traumatic formula by chemical penetration enhancers and to investigate the pharmacodynamic changes of the formula caused by incorporated enhancers. The effects of different enhancers on the transdermal absorption of piperine, the representative component of formula, were investigated by in vitro permeation studies. The tests showed an increasing enhancement effect in the following order: Azone/N-methylpyrrolidone (NMP) > oleic acid > Azone/peppermint oil > Azone/oleic acid > Azone/propylene glycol > Azone > peppermint oil > NMP > propylene glycol. The ratio and the content of the most effective enhancer Azone/NMP were determined subsequently. The results suggested that the most significant penetration enhancement was achieved by 3% (w/w) Azone/NMP (3:7). Furthermore, the in vivo pharmacodynamic responses of the formula suspension with or without Azone/NMP were compared using hot-plate assay and xylene-induced ears edema test as models. The data indicated that the formula had positive effect on analgesis and anti-inflammatory, which can be enhanced with the addition of enhancers.     

In vitro evaluation of a series of Azone analogs as dermal penetration enhancers: IV. Amines

Dermal enhancement properties of 12 novel amine enhancers (Azone analogs) were studied using in vitro diffusion cell techniques. Standard enhancers tested were Azone, didodecylamine, dodecylamine, and stearylamine. The synthesis of these novel compounds is presented. Hydrocortisone 21-acetate was used as the model drug and its transdermal permeation and skin retention were examined using hairless mouse skin. Enhancement ratios (ER) were determined for flux, 24 h diffusion cell receptor concentrations (Q24), and 24 h full-thickness skin steroid content. ER for all parameters for control was 1.00. Control was no pretreatment of the skin. All enhancers were applied at 0.4 M in propylene glycol 1 h prior to steroid application. N-dodecyldiethanolamine showed the greatest Q24 value (ER 56.16) while N-(2-methoxyethyl)dodecylamine showed the greatest skin retention (ER 2.0). Azone ER values were Q24 38.30 and skin retention 1.5, and those for didodecylamine were 13.06 and 1.1, respectively. In general, tertiary cyclic amine and secondary amine enhancers showed less activity for flux than the tertiary acyclic amine compounds.     

Effects of various absorption enhancers on transport of clodronate through Caco-2 cells

The major disadvantage concerning clinical use of bishosphonate drugs, like clodronate, is their poor and variable absorption after oral administration. The objective of this study was to assess the effects of four different absorption enhancers-palmitoyl carnitine chloride (PCC), N-trimethyl chitosan chloride (TMC), sodium caprate (C10), and ethylene glycol-bis(beta-aminoethyl ether)-N,N,N',N'-tetraacetic acid (EGTA)-on the transport of clodronate using Caco-2 cell culture model. The transport experiments were performed in a normal (1.3mM) and in a minimum-calcium concentration (apically calcium-free medium and basolaterally 100 microM calcium concentration). In the normal calcium concentration, a strong enhancement in clodronate permeation was observed with the enhancers: EGTA (2.5mM), TMC (1.5% w/v), and PCC (0.2mM) increased the transport of 1mM clodronate 190-, 20-, and 10-fold, respectively, and the transport of 10mM clodronate 130-, 70-, and 35-fold. In the minimum-calcium concentration, the effects of the absorption enhancers on the transport of clodronate were not so potent: TMC, PCC, and EGTA caused 2- to 20-fold enhancement in clodronate permeation whereas C10 (10mM) was without any effect. According to the results, the permeation of clodronate through Caco-2 cells could be significantly promoted by the absorption enhancers, which cause widening of the tight junctions and, thus, increase the permeability of the paracellular route.     

In situ and in vivo efficacy of peroral absorption enhancers in rats and correlation to in vitro mechanistic studies

The present investigation attempts to increase intestinal permeability and hence absorption of biopharmaceutic classification system (BCS) Class III (cefotaxime sodium (CX)) and Class IV (cyclosporin A (CSA)) drugs by employing certain absorption enhancers. Drugs were co-perfused with sodium caprate (SC, 0.25% w/v), piperine (P, 0.004% w/v) and sodium deoxycholate (SD, 1.0% w/v) separately in rat in situ single pass intestinal perfusion model. These additives increased intestinal permeability (P(app)) and absorption rate constant (K(a)) up to two and fourfold, respectively. SC exhibited substantial absorption enhancement of both CX and CSA, while SD and P enhanced absorption of CX and CSA, respectively. Co-administration of SC significantly enhanced peroral bioavailability of CX (from 29.4 +/- 1.7 to 69.6 +/- 3.2) and CSA (from 18.4 +/- 15.6 to 49.6 +/- 25.1) in rats, while P increased bioavailability of CSA (from 18.4 +/- 15.6 to 33.1 +/- 17.7). Transmission electron microscopy of intestinal mucosa revealed that SC and SD act on lipid and protein domains of absorptive membrane. P showed no effect on intestinal P(app) and oral bioavailability of CX but has a profound effect on CSA, a known P-glycoprotein (P-gp) substrate. These results indicated that P enhances intestinal absorption of CSA by modulating P-gp mediated efflux transport. Release of lactate dehydrogenase in situ from intestinal mucosa in the presence of absorption enhancer was taken as index of its local toxicity. All the absorption enhancers showed significantly less release of LDH compared to positive control, sodium dodecyl sulfate (60% w/v). Overall, the data indicate that the features of these commonly used food ingredients or endogenous bile salts can effectively improve bioavailability of various BCS Class III and Class IV drugs.     

In vitro evaluation of a series of azone analogs as dermal penetration enhancers: III. Acyclic amides

A scries of acyclic amides was synthesized and tested for enhancement properties using excised hairless mouse skin and hydrocortisone 21-acetate as the model drug. All compounds were applied at 0.4 M (or at their respective saturation solubilities) in propylene glycol. Azone (0.4 M) was used as a standard enhancer. Enhancement ratios were calculated for flux, 24 h diffusion cell receptor concentrations (Q₂₄) and 24 h full-thickness mouse skin steroid content. Enhancer 5 showed the highest activity for flux (35.22-fold over control), 24 h receptor concentration (79.86-fold over control) and skin drug content (4.3-fold over control). These enhancement ratios were higher than those for Azone which were 19.51, 38.30 and 1.5-fold over control, respectively. Enhancers 4, 10 and 11 showed similar Q₂₄ values to Azone, and 3, 9 and 10 increased skin steroid content to a greater extent than Azone.     

促渗剂对咪喹莫特体外经皮渗透的影响

目的研究几种促渗剂对咪喹莫特体外经皮渗透的影响。方法采用水平扩散池、离体SD大鼠腹部皮肤用渗透剂预处理的方法,测定接收液中咪喹莫特的含量及皮肤中药物的滞留量。结果在考察的促渗剂中,除卡必醇外(P>0.05),油酸、丙二醇、异硬脂酸、氮酮、月桂酸、松节油对咪喹莫特都有促渗作用;油酸、异硬脂酸能显著提高药物在皮肤中的滞留量(P<0.01),油酸对透过量影响不大(P>0.05);氮酮能使透过量显著增大(P<0.01),质量分数为3%的氮酮并不影响皮肤中的滞留量(P>0.05);松节油能使经皮透过量和皮肤中的滞留量都有所增加(P<0.05)。结论选用异硬脂酸作为咪喹莫特的渗透促进剂,该促渗剂能在不增加皮肤透过量的同时增加药物在皮肤中的滞留量。     

不同促透剂对人参皂苷Rg_1体外透皮吸收的影响

目的通过小鼠体外透皮实验,探讨不同促透剂对人参皂苷Rg1体外透皮吸收的影响,确定最佳促透剂,为研制新型透皮吸收制剂奠定基础。方法采用改良Franz扩散池法,以离体小鼠皮肤为透皮屏障,以生理盐水为接受介质,加入不同促透剂制备药液样品,以人参皂苷Rg1为定量指标成分进行体外透皮吸收检测,考察人参皂苷Rg1累计透过量。结果无促透剂条件下,人参皂苷Rg1未能透过;单一促透剂中以7%丙二醇效果最好,7%氮酮效果次之,冰片促透作用较小;复合促透剂中,氮酮+丙二醇组各浓度下累计透过量接近,氮酮+冰片组以两者质量浓度各为2.5%效果较好。结论常用促透剂丙二醇、氮酮、冰片均可增加药物中人参皂苷Rg1的透皮吸收量,其中,7%丙二醇为最佳促透剂。     

Buccal permeation of buspirone: mechanistic studies on transport pathways

The transport of buspirone across porcine buccal mucosa in vitro was investigated to elucidate the mechanisms of transport and permeation enhancement. The apparent permeability increased with an increase in pH to a lesser degree than the dependence of the partition coefficient. Whereas the lipophilic or apparent transcellular pathway was found to be the dominant buccal transport route for buspirone, ionized species contributed significantly to transport at acidic pH. At neutral pH, bile salts did not increase the flux of the lipophilic species of buspirone, and in contrast to its effect on stratum corneum, aqueous propylene glycol alone did enhance the flux of buspirone across buccal mucosa in vitro. The use of an enhancer combination containing 5% oleic acid, 40% propylene glycol in buffer resulted in the greatest flux, and this was consistent with the effect of this combined enhancer on the flux of lipophilic drugs across stratum corneum and the dominance of the transcellular pathway for buspirone at neutral pH.     

渗透促进剂对荜茇提取物中胡椒碱体外经皮吸收的影响

目的研究荜茇提取物中的主要成分胡椒碱的透皮吸收特性,确定最佳促进剂及质量浓度。方法采用卧式双室扩散池,以离体大鼠皮肤作为渗透屏障,用HPLC法测定样品中胡椒碱的质量浓度。以稳态流量(Js)、增渗比(ER)及滞后时间(tlag)为指标考察渗透促进剂对荜茇提取物中胡椒碱体外经皮吸收的影响。结果当用质量分数为10%的N-甲基-2-吡咯烷酮时,胡椒碱的稳态渗透速率最高。结论N-甲基-2-吡咯烷酮为荜茇提取物中胡椒碱经皮给药有效的渗透促进剂。     

三氧化二砷对表皮癌细胞株A-431增殖及Survivin表达的影响

目的探讨三氧化二砷（As2O3）对表皮癌细胞株A-431增殖和细胞周期的影响以及对Sur-vivin基因表达的影响,为As2O3治疗表皮癌提供实验室依据。方法培养表皮癌细胞A-431,加入不同浓度的As2O3,MTF法观察As2O3对A431细胞增殖的影响,应用流式细胞仪检测As203对A431细胞细胞周期、凋亡和Survivin基因表达的变化。应用Western Blot免疫印迹技术观察As2O3对A431细胞Survivin基因表达的影响。结果从浓度10μmol／L到40μmol／L,As2O3可以显著地抑制A431细胞的增殖,呈时间依赖性和浓度依赖性;As2O3影响A431细胞周期的分布,作用后G0／G1期期细胞群增多,凋亡数目增多（P〈0．05）。与对照组比较,As2O3能抑制A-431细胞Survivin基因的表达,该蛋白量下降（P〈0．05）。结论As2O3对体外培养的表皮癌细胞株有显著的增殖抑制作用,有诱导表皮癌凋亡的作用;并可能与抑制凋亡抑制基因Survivin的表达有关。     

Natural oils as skin permeation enhancers for transdermal delivery of olanzapine: in vitro and in vivo evaluation

The feasibility of development of transdermal delivery system of olanzapine utilizing natural oils as permeation enhancers was investigated. Penetration enhancing potential of corn (maize) oil, groundnut oil and jojoba oil on in vitro permeation of olanzapine across rat skin was studied. The magnitude of flux enhancement factor with corn oil, groundnut oil and jojoba oil was 7.06, 5.31 and 1.9 respectively at 5mg/ml concentration in solvent system. On the basis of in vitro permeation studies, eudragit based matrix type transdermal patches of olanzapine were fabricated using optimized concentrations of natural oils as permeation enhancers. All transdermal patches were found to be uniform with respect to physical characteristics. The interaction studies carried out by comparing the results of ultraviolet, HPLC and FTIR analyses for the pure drug, polymers and mixture of drug and polymers indicated no chemical interaction between the drug and excipients. Corn oil containing unsaturated fatty acids was found to be promising natural permeation enhancer for transdermal delivery of olanzapine with greatest cumulative amount of drug permeated (1010.68 μg/cm2/h) up to 24 h and caused no skin irritation. The fabricated transdermal patches were found to be stable. The pharmacokinetic characteristics of the final optimized matrix patch (T2) were determined after transdermal application to rabbits. The calculated relative bioavailability of TDDS was 113.6 % as compared to oral administration of olanzapine. The therapeutic effectiveness of optimized transdermal system was confirmed by tranquillizing activity in rotarod and grip mice model.     

Effect of penetration enhancers on the permeation of the thyrotropin releasing hormone analogue pGlu-3-methyl-His-Pro amide through human epidermis

The effect of the enhancers, cineole and ethanol, on the transdermal penetration of the tripeptide, pGlu-3-methyl-His2-Pro amide (M-TRH), across human epidermal membrane was studied by flow-through diffusion chambers. The aim of the study was to assess whether the biologically active analogue M-TRH displays similar transdermal penetration properties as those demonstrated earlier for the parental peptide, thyrotropin-releasing hormone (TRH) (Magnusson et al., 1997a Int. J. Pharm. 157, 113-121). Steady-state fluxes with a donor solution of phosphate-buffered saline (PBS) were 0.34 +/- 0.01 microgram/cm2h for M-TRH and 0.27 +/- 0.01 microgram/cm2h for TRH. Measured over 30 h the total amount penetrated was 8.6 +/- 1.0 and 7.8 +/- 1.7 micrograms/cm2, respectively. In the presence of 50% ethanol, the flux of the peptides increased approximately 3-fold. A donor solution of 3% cineole, in combination with 47% ethanol, increased the penetration of M-TRH to 1.60 +/- 0.02 micrograms/cm2h, compared to 0.92 +/- 0.03 microgram/cm2h for TRH, as reported previously. The corresponding total amount penetrated over 30 h was 41.5 +/- 4.9 and 24.9 +/- 1.7 micrograms/cm2, respectively. Our data suggests that enhancers added together with the penetrant can theoretically induce changes in the permeability of the stratum corneum sufficient to promote the transdermal absorption of therapeutically relevant amounts of these peptides. This demonstrates the possibility to deliver classes of compounds that have been viewed as not suitable for transdermal administration.     

Effects of absorption enhancers in chloroquine suppository formulations: I. In vitro release characteristics.

The need to develop chloroquine suppository formulations that yield optimal bioavailability of the drug has been emphasized. This study demonstrates the effects of incorporation of known absorption-enhancing agents (nonionic surfactants and sodium salicylate) on the in vitro release characteristics of chloroquine from polyethylene glycol (1000:4000, 75:25%, w/w) suppositories. The release rates were determined using a modification of the continuous flow bead-bed dissolution apparatus for suppositories. Results showed that the extent of drug release from suppositories containing any of three surfactants (Tween 20, Tween 80 and Brij 35) was 100%, whereas 88% release was obtained with control formulation (without enhancer) (P<0.05). However, Tween 20 was more effective than Brij 35 and Tween 80 in improving the drug release rate. There was a concentration-dependent effect with Tween 20, and 4% (w/w) of this surfactant was associated with the highest increase in the rate of drug release from the suppositories. Sodium salicylate at a concentration of 25% (w/w) also significantly enhanced the drug release rate, but a higher concentration of the adjuvant markedly reduced both the rate and extent of drug release. Combined incorporation of Tween 20 and sodium salicylate did not significantly modify (P0.05) the rate of drug release when compared to the effect of the more effective single agent. Due to their effects in improving the drug release profiles coupled with their intrinsic absorption-promoting properties, it is suggested that incorporation of 4% (w/w) Tween 20 and/or 25% (w/w) sodium salicylate in the composite polyethylene glycol chloroquine suppository formulations, may result in enhancement of rectal absorption of the drug. This necessitates an in vivo validation.     

Effect of chemical enhancers and iontophoresis on thiocolchicoside permeation across rabbit and human skin in vitro

The aim of this work was to study the permeation of thiocolchicoside across the skin in vitro. The effect of the chemical enhancer lauric acid and the physical technique of iontophoresis was investigated. Permeation experiments were performed in vitro using rabbit ear skin as barrier. The effect of lauric acid at different concentrations (2% and 4%) and of the vehicle (water, ethanol, or ethanol/water) was investigated. The primary effect of lauric acid was on the partitioning parameter, whereas the diffusive parameter did not change significantly. When human epidermis was used, the permeation parameters were generally lower, although not significantly different from rabbit ear skin. The data obtained with full-thickness human skin indicate that, despite the hydrophilic nature of thiocolchicoside, the resistance to drug transport is not limited to the stratum corneum, but that the underlying dermal tissue can also contribute. Iontophoresis enhanced the flux of thiocolchicoside compared with the passive control. The mechanism by which iontophoresis enhanced thiocolchicoside transport across the skin was electroosmosis. The permeation of thiocolchicoside across the skin can be enhanced using chemical or physical penetration enhancers.